A séance or seance (; French: [seɑ̃s]) is an attempt to communicate with spirits. The word séance comes from the French word for "session", from the Old French seoir, "to sit". In French, the word's meaning is quite general: one may, for example, speak of "une séance de cinéma" ("a movie session"). In English, however, the word came to be used specifically for a meeting of people who are gathered to receive messages from ghosts or to listen to a spirit medium discourse with or relay messages from spirits. In modern English usage, participants need not be seated while engaged in a séance.

Fictionalised conversations between the deceased appeared in Dialogues of the Dead by George, First Baron Lyttelton, published in England in 1760. Among the notable spirits quoted in this volume are Peter the Great, Pericles, a "North-American Savage", William Penn, and Christina, Queen of Sweden. The popularity of séances grew dramatically with the founding of the religion of Spiritualism in the mid-nineteenth century. Perhaps the best-known series of séances conducted at that time were those of Mary Todd Lincoln who, grieving the loss of her son, organized Spiritualist séances in the White House, which were attended by her husband, President Abraham Lincoln, and other prominent members of society. The 1887 Seybert Commission report marred the credibility of Spiritualism at the height of its popularity by publishing exposures of fraud and showmanship among secular séance leaders. Modern séances continue to be a part of the religious services of Spiritualist, Spiritist, and Espiritismo churches today, where a greater emphasis is placed on spiritual values versus showmanship.